[600MRG] restoring old crystals ??

[Merv Schweigert]

Ken is correct on all counts,  I have activated many old xtals
by cleaning the blanks and careful reassembly, all that was
need was good alcohol bath,   not rubbing alcohol but the
potent stuff from the pharmacy usually.  Do not touch the xtal
after cleaning, use "tongs" or something hold the edges and
put it back in the clean case.   Have had almost all bad ones
come back to life.   You will change the freq if you use acid
or any other "grinding" method.  I assume you want them to
stay on freq.
If grinding buffing compound mixed with water to a paste
works well,  comes in many grits,  a piece of flat plate
glass works as a bed.  the surface has to be perfectly flat
or the xtal is ruined as you grind.
GL   73 Merv K9FD/KH6
> On 5 Feb 2013 at 16:23, Neil Klagge wrote:
>
>> Thanks Ken. Ur comment "*It would be an excellent cleaner for the
>> crystals*" is just what I want to use it for. It might just activate
>> the crystal enough to oscillate.
>>
>> Neil
> Neil, I am assuming you are trying to reactivate FT-243 crystals: if so, there
> are a couple of other things besides CRYSTAL cleanliness you should think
> about.
>
> First, the two metal plates between which the crystal is held have raised bits
> at the four corners: those corners should contact the crystal in such a way
> that there is a small air-gap between the two metal plates and either surface
> of the crystal. Sometimes, folks have put those back in backwards, not
> realizing there are "lands" at each corner.
>
> Secondly, those metal plates must be totally clean. I use alcohol to clean
> those and handle them with clean tweezers.
>
> Thirdly, the entire interior of the holder must be as clean as a whistle. Alcohol
> works well here too.
>
> Fourthly, there should be two small thin copper plates which are connected
> to the pins. These usually are clamped when the crystal holder is closed up
> to the two metal plates mentioned above.
>
> Lastly, there should be a piece of flat rubber between the crystal holder's
> cover (the part with the three screws in it) and the spring that is supposed to
> press against the top connector and metal plate. There should be no
> electrical contact between either metal plate and the outside of the crystal.
>
> I have also seen some FT-243 holders in which the copper connectors are
> actually not making contact inside the pins. Sometimes, these can be
> resoldered.
>
> However, the most important factor is that the crystal itself must be
> scrupulously clean. You can use an old toothbrush and dishwashing
> detergent to scrub the heck out of it without hurting it. Get all the dirt,
> finger-grease, solder, flux, or anything else that is not "crystal" off and out of
> there.
>
> Good luck.
>
> Ken W7EkB
>
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